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<script>
  var climbStairs = function(n) {
    let dp = [];
    dp[0] = 0,dp[1] = 1,dp[2] = 2;
    for(let i = 3;i <= n;i++){
        dp[i] = dp[i-2] + dp[i-1];
    }
    return dp[n];
  };
</script>
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